The present invention relates to a driving control method of a glow plug that is mainly used to aid the start of a diesel engine, and in particular, to improvement of the stability and reliability of temperature control.
In the vehicle using a diesel engine, a glow plug has been used for aiding the starting, and the stability and reliability of the temperature control have a large influence on the quality of combustion, in other words, the quality of the engine operation. Accordingly, it is an important issue how the stable power control can be realized.
Therefore, for power control of the glow plug, various control methods have been proposed and put into practical use from various points of view (for example, refer to JP-A-2009-168319 and WO2010/001888 and the like).
Incidentally, the actual temperature characteristics (heating characteristics) of the glow plug, that is, the heating temperature when a certain voltage is applied varies relatively in many cases depending on each glow plug even if a so-called production lot is the same. This is even more so if the production lot is different.
On the other hand, as power control of the glow plug in a vehicle, for example, a method is generally adopted frequently in which an appropriate driving voltage according to various kinds of engine speeds and the load conditions of the engine is set in advance on the basis of the conduction characteristics of the standard glow plug and is stored in an electronic control unit, which controls the operation of the vehicle, the driving voltage is read at any time during the actual operation of the vehicle, and the glow plug is driven by the read voltage.
However, as described above, when the variation in the temperature characteristics of the glow plug mounted in the vehicle appears great, a difference occurs between the target temperature and the actual temperature of the glow plug for the voltage applied as described above. This may cause a problem in that it becomes difficult to ensure an appropriate combustion state.